1. Field of the Invention
This invention relates to a device for inserting additive video information, and particularly to a device for inserting additive video information such as a video ID for identifying a video signal having different aspect ratio.
2. Description of Related Art
There has been recently utilized a video signal source such as so-called Hi-vision, which is used for video signals having aspect ratio different from that of the U.S.A. and Japanese standard television system, that is, NTSC system, and also there have been developed various types of video display equipments such as television image receivers for the NTSC system which can display pictures in various frame shapes.
In addition, in a converting operation of a Hi-vision video signal to a video signal of NTSC system, not only a fixed video-signal conversion processing for displaying a picture in a fixed frame shape is carried out, but also the video display can be performed in various frame shapes and various kinds of video signal conversion processings can be arbitrarily combined with each other. In view of the foregoing, it has been also required that television image receivers for displaying pictures are so designed as to be usable for the video signal sources which have been subjected to the various kinds of signal conversion processings as described above.
For example, in a so-called MUSE-NTSC converter for converting a Hi-vision video signal to a video signal of a standard system (NTSC system), a signal having aspect ratio of 16:9 which is transmitted in a MUSE mode is converted to a video signal of the NTSC system (whose aspect ratio is 4:3). In this case, when the signal having aspect ratio of 16:9 is required to be recorded or displayed by an equipment adopting the aspect ratio of 4:3 of the NTSC system which is a conventional format, various kinds of video display frame modes as shown in FIG. 1 can be used. In FIG. 1, a represents a wide-frame mode for inserting a picture of 16:9 aspect ratio into a frame of 4:3 aspect ratio in a reduced-scale, b represents a zoom-frame mode for cutting lateral sides of a picture of 16:9 aspect ratio to obtain a picture of 4:3 aspect ratio and displaying it, and c represents a full-frame or squeeze-frame mode for compressing a picture of 16:9 aspect ratio in a lateral direction and inserting the laterally-compressed picture into a frame of 4:3 aspect ratio.
Therefore, when the video signal thus converted is recorded and reproduced by a VTR, or when a Hi-vision broadcast is received and displayed by a television image receiver of 4:3 aspect ratio using an adapter such as a MUSE-NTSC converter, there would occur a case where the video signal is reproduced in an erroneous frame shape or in an erroneous aspect ratio unless the video signal processing is switched to a proper one in accordance with an output mode of the MUSE-NTSC converter or a display frame mode of a television image receiver for displaying a picture.
In this case, when the video signal is recorded by the VTR or reproduced (displayed) by the television image receiver using the adapter (MUSE-NTSC converter), there are required cumbersome operations for confirming the mode which has been set in the MUSE-NTSC converter, and switching the video signal processing in accordance with a display mode of the television image receiver for displaying a picture.
In addition, it has been proposed to transmit as an additive video information an information (video ID, VID) on identification of a video signal format of aspect ratio as described above by utilizing a vertical blanking period of a television signal. In practical use, an operation of inserting or adding the identification information as described above into the vertical blanking period of the video signal in accordance with the set mode of the MUSE-NTSC converter has been manually carried out at all times.